Circuit breaker



Sept. 24, 1935. H. LANGFRITZ 2,015,598

CIRCUIT BREAKER Filed March 18, 1931 W/TA/ESSES. '5' INVENTOR Ai'TORNEY Hans Z 009797 72 An object of my invention is to provide a cirlass 1 UNITED STATES imreu r orrlca qmrnm;,

Application March 18, 1931, Serial No, 523,495

In Germany March 18, 1930 7 Claims. (01. zoo-ea) My invention relates to circuit breakers and particularlytocircuitbreakers used for controlling lighting circuits for residences, apartments, etc.,

and for controlling small motors.

' cuit breaker that shall be trip-free of the operatmg handle and which shall be released'to' open position by an electro-magnet which shall also serve as a blowout magnet. i 1,.

Another object or my invention is to-prov ide a circuit breaker having the above noted characteristics. wherein the circuit breaker will be tripped to open position, under overload conditions by a current-responsive thermally-actuated latchdevice. i H

A further object of my invention isto provide a circuit breaker wherein the blowout magnet winding shall be mounted beneath the supporting base of the circuit breaker and wherein the pole pieces of the magnet shall extend through the base and be disposed substantially parallel to the side walls of the arc chute and wherein an armature for tripping the circuit breaker shall be disposed adjacent to the ends of the pole pieces in a flux path parallel with that of the fiux path between the pole pieces that constitutes the blowout field.

A still further object of my invention is-to provide a compact and relatively inexpensive circuit breaker that may be readily assembled and be rugged in construction. I

These and other objects that will be made apparent throughout the further description of my invention are obtained by means of the circuit breaker hereinafter described, and illustrated in thaaccompanying drawing, wherein Figure 1 is a side elevational view, partially in section, of a circuit breaker embodying the features of my invention;

Fig. 2 is an end elevational view of the circuit breaker shown in Fig. 1, the cover being shown in a section;

Fig. 3 is an elevational view of a fragment of the circuit breaker shown in Fig. 1, the contactoperating parts being shown in their closed positions;

Fig. 4 is an elevational view of a fragment of the circuit breaker illustrating the operative position of the electromagnet trip member and the contact-operating parts when the circuit breaker is in closed position, and

Fig. 5 is an elevational view of a bimetal thermal element.

Referring to the drawing, the circuit breaker comprises an insulating base 5, having a recess 6 in its underside, and which supports, on its outer face, a stationary contact plate I having its terminal extending, through the base, into the recess 6, where it is provided with a conductor-terminal screw 8 which serves to secure a conductor (not shown) to the contact terminal.

A sheet-metal supporting frame 9 is mounted 5 on the outer face of the base which serves to support the operating mechanism of the circuit breaker.

'Ifhe circuit breaker-operating mechanism comprises a contact arm I I that is pivotally 10 mounted on the frame 9 for rotative movement about a pivot shaft l2. The arm is provided with a flexible contact strap II which carries, at its free end, a movable contact 14 that is adapted to engage the stationary contact I when the switch 15 arm is moved to the closed position, indicated in Fi 3.

A switch arm I I is moved to open and to closed position by means 01' an insulating operating handle l5 that is pivotally mounted upon theframe 9 20 for rotation about the pivot shaft IS. The handle is connected to the, contact arm II by means of a pair of toggle links I! and I8 that are joined by a knee pivot l9 and are pivotally connected to the operating handle 15 and the switch arm II by 5 means of pivot shafts 2i and 22, respectively.

As indicated in Fig. 3, the toggle links H and I8 are in their made position wherein the knee pivot l 9 lies beneath a center line A through the pivot shafts l6 and 22, the relative movement of 30 the links in one direction being limited by a stop 23 carried on the link I8 which engages the link I'I. Upward movement of the knee pivot I! of the toggle past the center line A causes the collapse of the toggle and permits the spring 24 that 35 is connected to the frame 9 and to the contact arm II to move the switch arm to open position with a snap action. F

When the switch is in the open position, the toggle links occupy the position shown in Fig. 1 40 where they are again in the made position and will cause the switch arm to be moved to closed position when theoperating handle is moved in a clockwise direction.

An insulating arc chute 25, having spaced side 45 walls 26 disposed on opposite sides of the contact.

I, is provided for surrounding the contacts I and apairofpolepieces II that extendthroughan opaningflinthebase I andare disposed exteriorly of the arc chute and in parallel relation to the side walls thereof. The winding II of the blowout magnet surrounds the central portion of the core member 21 and is disposed in the .recess I of the base I where it is protected by the insulating base, from exposure to the are drawn between the contacts. The flux lines passing from one pole piece to the other cross the path of the are drawn between the contacts 1 and I4 and serves to move it upwardly out of the chute and extinguish it in a well known manner.

In order to render the circuit breaker responsive to severe overload and short-circuit conditions, a trip arm II of U-shape is provided that is pivoted for rotation about a shaft II mounted on the frame I. The trip arm I2 is provided with an extension 34 that extends beneath the knee pivot II, and the free end of the trip arm I! is provided with an iron armature 35 that is disposed exteriorly of the chute 25 and adjacent to the outer ends of the pole pieces 28 of the blowout magnet. The magnet winding 3| is connected in series with the contacts 1 and i4 and, consequently, a sudden current surge, such as is produced by a severe overload or short-circuit condition, attracts the armature 35 toward the ends or the pole pieces. This movement causes the arm 34 on the trip arm 32 to strike the knee pivot i I and move it upwardly across the center line A and thereby trip the switch arm to open position. By reason of the fact that the armature is connected in parallel with the blowout flux path, considerable attractive force is exerted by the pole pieces, and it has been found that a very small armature is required. The armature, therefore, while shunting the flux path, does not materially reduce the strength of the blowout field because of its relatively small cross-sectional area. Therefore, the arrangement is particularly advantageous and does not materially aflect the ability of the blowout magnet to move and extinguish the arc.

In order to cause the circuit breaker to trip 'open under relatively small overloads after a predetermined duration thereof, I have provided a second trip arm 36 that is mounted for rotative movement about the pivot shaft i8 and is normally biased toward the knee pivot I! by means of a spring 31 that is connected between a latch arm a on the trip arm 38, and the frame 9, as indicated in Figs. 1 and 3. The trip arm 36 is I normally restrained by a bimetal element 38 of U-shape, as indicated in Fig. 5, which normally engages a latch ll on the free end of the latch arm II. The bimetai element 39 is also connected in series with the contacts I and 8 and is so proportioned that an overload which endures for a predetermined time will cause it to be deflected sufficiently to release the latch ii and permit the spring IT to move the trip arm 36 in the counterclockwise direction with a snap action. The arm strikes the underside of the knee pivot i9 'and causes the collapse of the toggle. The bimetal element isprovided with a conductive bridging strap 42 that is adiustably attached to the bimetal element by screws 43, and by shifting the position of the bridging strap, the calibration of the face of the insulating base I, the operating handle extending through a slot in the cover for rendering it accessible exteriorly thereof.

From the foregoing description, it is apparent that I have provided a simple and inexpensive form of circuit breaker that is responsive tossvere overload and short-circuit-current conditions and is also responsive to relatively small overloads which endure for a predetermined time.

While I have illustrated only one embodiment 1 of my invention, it will be apparent to those skilled in the art that various changes. modifications, substitutions, additions and omissions may be made in the apparatus illustrated without departing from the spirit and scope of my invention as 1 set forth in the appended claims.

I claim as my invention:

1. A circuit breaker comprising an insulating base having a recess in its underside, a contact member disposed on the outer side of the base, an I are chute having side walls disposed at opposite sides of the contact member, a movable contact member movable within the arc chute and engaging the first contact member, and a blowout msgnet of U-shape having its pole pieces extending a through the base and substantially parallel with i the said side walls and having its winding disposed in the said recess, and an armature movable to a position bridging across the end portions of I said U-shaped blowout magnet to trip the breaker. s

2. A circuit breaker comprising an insulating base having a recess in its underside, a contact member disposed on the outer side of the base, an arc chute having side walls disposed at opposite sides of the contact member, a movable I contact member movable within the arc chute and engaging the first contact member, a blowout magnet of U-shape having its pole pieces extending through the base and substantially parallel with the said side walls and having its winding 44 disposed in the said recess, and an armature cooperating with the pole pieces for tripping the circuit breaker.

3. In a circuit interrupter, an arc chute, a pair of separable contacts for drawing an arc in said 4' arc chute, biasing means for moving one of said contacts to separated position, a magnetic blowout for the are drawn between said contacts including pole pieces of magnetic material having substantially all of the end portions thereof extend- 5i ing along opposite sides of the are chute with an air gap therebetween traversed by the magnetic flux whereby substantially all of the flux in the space between the pole pieces extends across the arc chute for moving the arc, and a movable ar- N mature magnetically in parallel with the magnetic flux path across said air gap, said armature when moved initiating movement of said contact to separated position by said biasing means.

4. In a circuit interrupter, a movable contact I for opening and closing the'circuit, a blowout magnet for the arc drawn by said movable contact including a coil having a core of magnetic -material extending therethrough and a pair of pole pieces rigid with said core and having only 0| one pair of end portions, said pair of end portions extending to opposite sides of the path of movement of said movable contact and having a gap traversed by the magnetic ilux set up by said coil for moving the arc, and an armature of magnetic 1! material movable by the magnetic flux set up by said coil and positioned magnetically in parallel with the magnetic flux path across said gap between said pole pieces, said armature when moved causing said movable contact to open the circuit. ll

5. In a circuit interrupter, means for drawing an are, means of magnetic material energized by the current flow through the circuit interrupter for providing a magnetic blowout field transverse to the axis of said arc, and means for initiating the drawing of said arc upon the occurrence of predetermined conditions, said means including an armature of magnetic material positioned magnetically in parallel with at least that portion of the magnetic field which is transverse to the axis of the arc, and thermally responsive means for also initiating the drawing of said are, said thermally responsive means being operable without movement of said armature toward said means of magnetic material.

6. In a circuit interrupter, a movable contact for opening and closing the circuit, a blowout magnet for the are drawn by said movable contact including means providing a magnetic circuit having only a single air gap therein, said magnetic means being positioned with said movable contact in said air gap, and a movable armature of magnetic material positioned magnetically in parallel with the magnetic flux path across said air gap, said armature when moved by the magnetic flux causing opening of said movable contact. 7. In a circuit interrupter, an arc chute, a pair of separable contacts for drawing an arc in said arc chute, biasing means for moving one of said contacts to separated position, a magnetic blowout for the are drawn between said contacts including pole pieces of magnetic material having substantially the whole end portions thereof extending along opposite sides of the arc chute with an air gap therebetween traversed by the magnetic flux whereby substantially all of the flux in the space between the pole pieces extends across the arcchute for moving the arc, and a movable armature magnetically in parallel with 1 the magnetic flux path across said air gap, said armature when moved initiating movement of said contact to separated position by said biasing means, and a thermal element responsive to electrical conditions in the circuit for also initiating g movement of said contact to separated position by said biasing means, said thermal element being operable without movement of said armature toward said pole pieces.

' HANS LANGFRITZ. 

